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dmaengine: at_hdmac: Fix concurrency over the active list

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The tasklet (atc_advance_work()) did not held the channel lock when
retrieving the first active descriptor, causing concurrency problems if
issue_pending() was called in between. If issue_pending() was called
exactly after the lock was released in the tasklet (atc_advance_work()),
atc_chain_complete() could complete a descriptor for which the controller
has not yet raised an interrupt.

Fixes: dc78baa2b9 ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by: Peter Rosin <peda@axentia.se>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221025090306.297886-1-tudor.ambarus@microchip.com
Link: https://lore.kernel.org/r/20221025090306.297886-11-tudor.ambarus@microchip.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Tudor Ambarus 2022-10-25 12:02:44 +03:00 • committed by Vinod Koul
commit 03ed9ba357
1 changed files with 6 additions and 4 deletions
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10
drivers/dma/at_hdmac.c
View file

@ -462,8 +462,6 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
if (!atc_chan_is_cyclic(atchan))
dma_cookie_complete(txd);
/* Remove transfer node from the active list. */
list_del_init(&desc->desc_node);
spin_unlock_irqrestore(&atchan->lock, flags);
dma_descriptor_unmap(txd);
@ -495,6 +493,7 @@ atc_chain_complete(struct at_dma_chan *atchan, struct at_desc *desc)
*/
static void atc_advance_work(struct at_dma_chan *atchan)
{
struct at_desc *desc;
unsigned long flags;
dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");
@ -502,9 +501,12 @@ static void atc_advance_work(struct at_dma_chan *atchan)
spin_lock_irqsave(&atchan->lock, flags);
if (atc_chan_is_enabled(atchan) || list_empty(&atchan->active_list))
return spin_unlock_irqrestore(&atchan->lock, flags);
spin_unlock_irqrestore(&atchan->lock, flags);
atc_chain_complete(atchan, atc_first_active(atchan));
desc = atc_first_active(atchan);
/* Remove the transfer node from the active list. */
list_del_init(&desc->desc_node);
spin_unlock_irqrestore(&atchan->lock, flags);
atc_chain_complete(atchan, desc);
/* advance work */
spin_lock_irqsave(&atchan->lock, flags);